Process

ABSTRACT

The present invention relates to an improved process for the preparation of heterocyclyl substituted adenosine derivatives. More particularly the invention is concerned with preparation of particular physical forms of (2S, 3S, 4R, 5R)-2-(5 tert-butyl-[1,3,4]oxadiazol-2-yl)-5-[6-(4-chloro-2-fluoro-phenylamino)-9H-purin-9-yl]tetrahydro-furan-3, 4-diol.

The present invention relates to an improved process for the preparationof heterocyctyl substituted adenosine derivatives. More particularly theinvention is concerned with preparation of particular physical forms of(2S, 3S, 4R, 5R)-2-(5tert-butyl-[1,3,4]oxadiazol-2-yl)-5-[6-(4-chloro-2-fluoro-phenylamino)-9H-purin-9-yl]-tetrahydro-furan-3,4-diol,pharmaceutical compositions thereof and its use in therapy.

(2S, 3S, 4R, 5R)-2-(5tert-Butyl-[1,3,4]-oxadiazol-2-yl)-5-[6-(4-chloro-2-fluoro-phenylamino)-9H-purin-9-yl]-tetrahydro-furan-3,4-diolhas activity at the Adenosine A1 receptor.

WO 99/67262 (Glaxo Group Limited) discloses certain heterocyclyladenosine derivatives including(2S,3S,4R,5R)-2-(5-tert-butyl-[1,3,4]-oxadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diol,Example 14 of WO 99/67262, the structure of which is indicated below asthe compound of formula (A):

The preparation of the compound of formula (A) (hereinafter referred toas Compound A) is described in WO 99/67262. Compound A may be preparedby the reaction of 4-chloro-2-fluoroaniline with an appropriate purinylderivative having a suitable leaving group in the 6-position of thepurine ring, optionally in the presence of a solvent at elevatedtemperatures. Alternatively Compound A may be prepared by treating9-{(3aR,4R,6S,6aR)-6-[5-tert-butyl-1,3,4-oxadiazol-2-yl]-2,2-dimethyltetrahydrofuro[3,4-d][1,3]dioxol-4-yl}-N-(4-chloro-2-fluorophenyl)-9H-purin-6-aminewith trifluoroacetic acid followed by treatment with sodium bicarbonate.Extraction of the product into ethyl acetate followed by evaporation invacuo provides Compound A as a buff solid.

Compound A can be obtained in polymorphic forms.

Compound A may be obtained by crystallisation under certain conditionsin the form of polymorphic form I (hereinafter Polymorph I).

It has also been found that Compound A may also be crystallised in theform of polymorphic form II (hereinafter Polymorph II).

Polymorph I exhibits enhanced stability over Polymorph II at ambienttemperatures, for example 15-20° C.

Polymorph II exhibits enhanced stability over Polymorph I at elevatedtemperatures, for example temperatures in excess of 70° C.

Polymorph I and Polymorph II may be useful in the preparation ofpharmaceutical formulations.

(2S,3S,4R,5R)-2-(5-tert-Butyl-[1,3,4]-oxadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diolmay be prepared in polymorphic form by crystallisation of the compoundunder suitable conditions.

In general,(2S,3S,4R,5R)-2-(5-tert-butyl-[1,3,4]-oxadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diolin the form of Polymorph I may be obtained by crystallisation of thecompound by heating in N,N-dimethylformamide at a temperature sufficientto effect dissolution, for example 70-90° C., and initiatingcrystallisation by controlled addition of water until turbidity results,and allowing to cool to ambient temperature, for example 15-25° C.

Alternatively,(2S,3S,4R,5R)-2-(5-tert-butyl-[1,3,4]-oxadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diolin the form of Polymorph I may be obtained by reacting9-{(3aR,4R,6S,6aR)6-[5-tert-butyl-1,3,4-oxadiazol-2-yl]-2,2-dimethyltetrahydrofuro[3,4-d][1,3]dioxol-4-yl}-(4-chloro-2-fluorophenyl)-9H-purin-6-aminewith trifluoroacetic acid/water, neutralisation with aqueous methanolicammonia solution, at 25-50° C. over at least one hour followed bycooling to 0-5° C.

In general,(2S,3S,4R,5R)-2-(5-tert-butyl-[1,3,4]-oxadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diolin the form of Polymorph II may be obtained by crystallisation of thecompound by heating in methyl isobutyl ketone at reflux (117-118° C.)and allowing to cool to ambient temperature, for example 15-25°C.

Polymorph I and Polymorph II have been characterised by X-ray powderdiffraction (XRPD) studies and Raman spectroscopy as shown in FIGS. 1and 2.

Polymorph I is characterised by having peaks in its Raman spectra at3429, 3414 and 76 cm⁻¹, especially at 3141 and 76 cm⁻¹.

Polymorph II is characterised by having peaks in its Raman spectra at3424, 1615 and 92 cm⁻¹.

Raman peaks are quoted to the nearest cm⁻¹.

Polymorph I is characterised by having an XRPD pattern with signals at4.32, 4.99, 6.23, 6.97, 8.64, 10.04, 12.53, and 14.47 (degrees 2-theta).

Polymorph II is characterised by having an XRPD pattern with signals at4.74, 5.34, 6.63, 7.87, 8.31, 8.93, 10.71, and 13.98 (degrees 2-theta).

The skilled person will recognise that XRPD peak positions are affectedby differences in sample height. The peak positions quoted herein arethus subject to a variation of +/−0.15 degrees 2-theta.

When prepared using the known procedures mentioned above, the crystalsof Polymorph I and Polymorph II are obtained in a highly fibrous crystalhabit which makes the materials difficult to handle. Furthermore,difficulty may be experienced in controlling the polymorphic form of theisolated product.

The present invention provides a process for the preparation ofPolymorph I in a crystal habit that is easy to handle, and offerscontrol over polymorphic form.

Accordingly, in a first aspect, the present invention provides a processfor preparing(2S,3S,4R,5R)-2-(5-tert-butyl-[1,3,4]-oxadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diol(Compound A) as Polymorph I comprising:

-   a) dissolving Compound A in N,N-dimethylformamide and water wherein    the N,N-dimethylformamide:water ratio is in the range 2.5:1 to 1.5:1    and the dilution is at least 15 volumes; and-   b) initiating crystallisation by either: adjusting the temperature    to less than 25° C.; or adjusting the temperature to less than 30°    C., and seeding with Polymorph I; and-   c) optionally, adding toluene.

In a preferred aspect the solution of compound A is treated withdecolourising charcoal prior to adjusting the temperature.

Preferably the N,N-dimethylformamide:water ratio during thecrystallisation is in the range from 2.2:1 to 1.8:1, more preferably theratio is 2:1.

Preferably the dilution of the solution prior to crystallisation ofPolymorph I is 15 to 40 volumes, more preferably 15 to 30 volumes.

Preferably the solution of Compound A is cooled to 20-29° C., morepreferably 25-28° C. prior to seeding.

When toluene is added during the preparation of Polymorph I, preferablyit is added in an amount in the range of 1 to 5 volumes, more preferably1 to 2 volumes.

In a preferred embodiment the present invention provides a process forpreparing(2S,3S,4R,5R)-2-(5-tert-butyl-[1,3,4]-oxadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diol(Compound A) as Polymorph I comprising:

-   a) dissolving Compound A in N,N-dimethylformnamide and water wherein    the N,N-dimethylformamide:water ratio is in the range 2.5:1 to 1.5:1    and the dilution is at least 15 volumes; and-   b) initiating crystallisation by adjusting the temperature to less    than 250° C. and seeding with Polymorph I; and-   c) adding toluene.

In an alternative embodiment the present invention provides a processfor preparing(2S,3S,4R,5R)-2-(5-tert-butyl-[1,3,4]-oxadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diol(Compound A) as Polymorph I comprising:

-   a) reacting    9{(3aR,4R,6S,6aR)-6-[5-tert-butyl-1,3,4-oxadiazol-2-yl]-2,2-dimethyltetrahydrofuro[3,4-d][1,3]dioxol-4-yl}N-(4-chloro-2-fluorophenyl)-9H-purin-6-amine    with trifluoroacetic acid/water; and-   b) neutralisation with aqueous methanolic ammonia solution at    25-50° C. over at least one hour; and-   c) cooling to 0-5° C., and optionally adding toluene.

Suitable temperatures for the reaction of9-{(3aR,4R,6S,6aR)-6-[5-tert-butyl-1,3,4-oxadiazol-2-yl]-2,2-dimethyltetrahydrofuro[3,4-d][1,3]dioxol-4-yl}-N-(4-chloro-2-fluorophenyl)-9H-purin-6-aminewith trifluoroacetic acid/water include ambient temperature, e.g.15-250° C. Suitably the TFA/water ratio is 20:1 to 5:1 v/v, preferably12:1 to 7:1 v/v.

Suitably the neutralisation step is carried out over 1-2 hours.Preferably the reaction temperature is maintained at a temperature of35-45 ° C. throughout the neutralisation.

Suitably the reaction mixture is cooled to 0-5° C. over at least 1 hour,preferably 1 to 2 hours.

In a preferred embodiment toluene is added to the reaction mixture.

The crystal habit of Polymorph I prepared according to the presentinvention is of a spheronised habit as indicated in the photographicimages in FIG. 3.

The present invention therefore further provides Polymorph I inspheronised habit. The invention also provides Polymorph I inspheronised habit substantially free of alternative habits.

A further aspect of the present invention is Polymorph I in a habitobtainable by a process of the present invention.

The present invention further provides a process for the preparation ofPolymorph II in a crystal habit that is easy to handle, and offerscontrol over the polymorphic form obtained.

Accordingly, the present invention additionally provides a process forpreparing(2S,3S,4R,5R)-2-(5-tert-butyl-[1,3,4]-oxadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diol(Compound A) as Polymorph II comprising:

-   a) dissolving Compound A in N,N-dimethylformamide and water wherein    the N,N-dimethylformamide:water ratio is in the range 2:1 to 1:2 and    the dilution is at least 15 volumes; and-   b) initiating crystallisation by either: adjusting the temperature    to greater than 35° C.; and optionally seeding with polymorph II;    and-   c) optionally, adding toluene.

In a preferred aspect the solution of Compound A is treated withdecolourising charcoal prior to adjusting the temperature and seeding.

Preferably the N,N-dimethylformamide:water ratio during crystallisationof Polymorph II is in the range of 1.8:1 to 1.2:1, more preferably 1.5:1to 1.3:1, yet more preferably 1.4:1.

Preferably the dilution of the solution prior to crystallisation ofPolymorph Il is 15 to 40 volumes, more preferably 15 to 30 volumes.

Preferably the temperature of the solution of Compound A is adjusted to35-120° C., more preferably 50-70° C. yet more preferably 50-55° C.,prior to crystallisation of Polymorph II.

When toluene is added during the preparation of Polymorph II, preferablyit is added in an amount in the range of 1 to 5 volumes, more preferably1 to 2 volumes.

In a preferred embodiment the present invention further provides aprocess for preparing(2S,3S,4R,5R)-2-(5-tert-butyl-[1,3,4]-oxadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diol(Compound A) as Polymorph II comprising:

-   a) dissolving Compound A in N,N-dimethylformamide and water wherein    the N,N-dimethylformamide:water ratio is in the range 1.5:1 to 1.3:1    and the dilution is at least 15 volumes; and-   b) initiating crystallisation by adjusting the temperature to    greater than 35° C.; and seeding with polymorph II; and-   c) adding toluene.

Preferably the N,N-dimethylformamide:water ratio during crystallisationof Polymorph II is 1.4:1.

The crystal habit of Polymorph II prepared according to the presentinvention is of a spheronised habit as indicated in the photographicimages in FIG. 3.

The present invention therefore further provides Polymorph II inspheronised habit. The invention also provides Polymorph II inspheronised habit substantially free of alternative habits.

A further aspect of the present invention is Polymorph II in a habitobtainable by a process of the present invention.

By “substantially free” is meant containing less than 10%, preferablyless than 5%, more preferably less than 2%, of alternative habits.

When used herein the dilution term “volumes” means millilitres (mL) ofsolvent per gram of Compound A. For example, 10 volumes means 10 mL ofsolvent per 1 g of Compound A.

The invention provides a pharmaceutical composition comprising polymorphI of(2S,3S,4R,5R)-2-(5-tert-butyl-[1,3,4]oxadiazol-2-yl)-S-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diolin a habit obtainable by a process of the present invention and apharmaceutically acceptable carrier and/or excipient.

This invention further provides a pharmaceutical composition comprisingpolymorph I of(2S,3S,4R,5R)-2-(5-tert-butyl-[1,3,4]oxadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diolin spheronised habit, and a pharmaceutically acceptable carrier and/orexcipient.

The invention also provides a method of treating a patient sufferingfrom a condition where there is an advantage in decreasing plasma freefatty acid concentration, or reducing heart rate, or treating a patientsuffering from ischemic heart disease, peripheral vascular disease,stroke, pain, CNS disorder, or sleep apnoea comprising administering atherapeutically effective amount of Polymorph I of(2S,3S,4R,5R)-2-(5-tert-butyl-[1,3,4]-oxadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diolin a habit obtainable by a process of the present invention.

The present invention also provides a method of treating a patientsuffering from a condition where there is an advantage in decreasingplasma free fatty acid concentration, or reducing heart rate, ortreating a patient suffering from ischemic heart disease, peripheralvascular disease, stroke, pain, CNS disorder, or sleep apnoea comprisingadministering a therapeutically effective amount of Polymorph I of(2S,3S,4R,5R)-2-(5-tert-butyl-[1,3,4]-oxadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diolin spheronised habit.

Polymorph I of(2S,3S,4R,5R)-2-(5-tert-butyl-[1,3,4]-oxadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diolin a habit obtainable by a process of the present invention may be usedfor decreasing plasma free fatty acid concentration; reducing heartrate; or treating ischemic heart disease, peripheral vascular disease,stroke, pain, CNS disorder, or sleep apnoea, as described in WO99/67262.

Polymorph I of(2S,3S,4R,5R)-2-(5-tert-butyl-[1,3,4]-oxadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diolin spheronised habit may be used for decreasing plasma free fatty acidconcentration; reducing heart rate; or treating ischemic heart disease,peripheral vascular disease, stroke, pain, CNS disorder, or sleepapnoea, as described in WO 99/67262.

Polymorph I of(2S,3S,4R,5R)-2-(5-tert-butyl-[1,3,4]-xadiazol-2-yl)-5-[6(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diolin a habit obtainable by a process of the present invention may be usedin the manufacture of a medicament for use in decreasing plasma freefatty acid concentration; reducing heart rate; or treating ischemicheart disease, peripheral vascular disease, stroke, pain, CNS disorder,or sleep apnoea, as described in WO 99/67262.

Polymorph I of(2S,3S,4R,5R)-2-(5-tert-butyl-[1,3,4]-oxadiazol-2-yl)5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diolin spheronised habit may be used in the manufacture of a medicament foruse in decreasing plasma free fatty acid concentration; reducing heartrate; or treating ischemic heart disease, peripheral vascular disease,stroke, pain, CNS disorder, or sleep apnoea, as described in WO99/67262.

This invention further provides for a pharmaceutical compositioncomprising Polymorph II of(2S,3S,4R,5R)-2-(5-tert-butyl-[1,3,4]oxadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diolin a habit obtainable by a process of the present invention, and apharmaceutically acceptable carrier and/or excipient.

This invention further provides for a pharmaceutical compositioncomprising Polymorph II of(2S,3S,4R,5R)-2-(5-tert-butyl-[1,3,4]oxadiazol-2-yl)-5-[6(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diolin spheronised habit, and a pharmaceutically acceptable carrier and/orexcipient.

The invention also provides a method of treating a patient sufferingfrom a condition where there is an advantage in decreasing plasma freefatty acid concentration, or reducing heart rate, or treating a patientsuffering from ischemic heart disease, peripheral vascular disease,stroke, pain, CNS disorder, or sleep apnoea comprising administering atherapeutically effective amount of Polymorph II of(2S,3S,4R,5R)-2-(5-tert-butyl-[1,3,4]-oxadiazol-2-yl)-5-[6(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diolin a habit obtainable by a process of the present invention.

The invention also provides a method of treating a patient sufferingfrom a condition where there is an advantage in decreasing plasma freefatty acid concentration, or reducing heart rate, or treating a patientsuffering from ischemic heart disease, peripheral vascular disease,stroke, pain, CNS disorder, or sleep apnoea comprising administering atherapeutically effective amount of Polymorph II of(2S,3S,4R,5R)-2-(5tert-butyl-[1,3,4]-oxadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diolin spheronised habit.

Polymorph II of(2S,3S,4R,5R)-2-(5tert-butyl-[1,3,4]-oxadiazol-2-yl)-5-[6-(4-chloro2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diolin a habit obtainable by a process of the present invention may be usedfor decreasing plasma free fatty acid concentration; reducing heartrate; or treating ischemic heart disease, peripheral vascular disease,stroke, pain, CNS disorder, or sleep apnoea, as described in WO99/67262.

Polymorph II of(2S,3S,4R,5R)-2-(5tert-butyl-[1,3,4]-oxadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diolin spheronised habit may be used for decreasing plasma free fatty acidconcentration; reducing heart rate; or treating ischemic heart disease,peripheral vascular disease, stroke, pain, CNS disorder, or sleepapnoea, as described in WO 99/67262.

Polymorph II of(2S,3S,4R,5R)-2-(5tert-butyl-[1,3,4]-xadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diolin a habit obtainable by a process of the present invention may be usedin the manufacture of a medicament for use in decreasing plasma freefatty acid concentration; reducing heart rate; or treating ischemicheart disease, peripheral vascular disease, stroke, pain, CNS disorder,or sleep apnoea, as described in WO 99/67262.

Polymorph II of(2S,3S,4R,5R)-2-(5-tert-butyl-[1,3,4]-oxadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diolin spheronised habit may be used in the manufacture of a medicament foruse in decreasing plasma free fatty acid concentration; reducing heartrate; or treating ischemic heart disease, peripheral vascular disease,stroke, pain, CNS disorder, or sleep apnoea, as described in WO99/67262.

Suitable pharmaceutically acceptable carriers and excipients aredescribed in WO 99/967262.

WO 99/67262 (Glaxo Group Limited) is incorporated by reference herein asthough fully set forth.

The following examples illustrate the invention but are not intended asa limitation thereof.

The following examples illustrate aspects of this invention but shouldnot be construed as limiting the scope of the invention in any way.

EXAMPLES

Unless otherwise indicated, (2S,3S,4R,5R)-2-(5-tert-Butyl-[1,3,4]oxadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diol(Compound A) was prepared according to the methods described in WO99/67262.

Example 1 (2S, 3S, 4R, 5R)-2-5tert-Butyl-[1,3,4]oxadiazol-2-yl)-5-[6-(4-chloro-2-fluoro-Phenylamino)-9H-purin-9-yl]-tetrahydro-furan-3,4-diol(Compound A) Polymorphic Form I

Compound A (337 g) was dissolved in a warm mixture ofN,N-dimethylformamide (DMF, 3.37 L) and water (1.12 L). Decolourisingcharcoal (84.2 g) was added and the suspension stirred at 60° C. for 1hour. The charcoal was removed by filtration and the filter washed witha mixture of DMF (1.12 L) and water (374 mL). The combined filtrate andwash was then cooled to 25-28° C. Water (740 mL) was added and thesolution seeded with Compound A (Polymorph I). The resulting suspensionwas then stirred overnight at 20-25° C. Water (2.25 L) was added and thesuspension stirred for 2 hours. Toluene (472 mL) was added and theproduct collected by filtration, washed with 1:1 aqueous DMF (840 mL)and water (8.4 L), and then dried in vacuo at 40-45° C. to give CompoundA (Polymorph I) as an off white solid (277.5 g, 82% recovery).

Example 2 (2S, 3S, 4R, 5R)-2-(5tert-Butyl-[1,3,4]oxadiazol-2-yl)-5-[6-(4chloro-2-fluoro-phenylamino)-9H-purin-9-yl]-tetrahydro-furan-3,4-diol(Compound A) Polymorphic Form II

Compound A (20 g) was dissolved in a warm mixture ofN,N-dimethylformamide (DMF, 200 mL) and water (100 mL). Decolourisingcharcoal (5.0 g) was added and the suspension stirred at 60° C. for 1hour. The charcoal was removed by filtration and the filter washed witha mixture of DMF (66.6 mL) and water (33.3 mL). The temperature of thecombined filtrate and wash was adjusted to 50-55° C., water (53.4 mL)was added and the solution seeded with Compound A (Polymorph II). Theresulting suspension was then stirred overnight at 50-55° C. Water (80mL) was added and the suspension stirred for 2 hours. The mixture wasthen cooled to 20-25° C. and stirred at this temperature for 1 hour.Toluene (28 mL) was added and the product collected by filtration,washed with 1:1 aqueous DMF (50 mL) and water (500 mL), and then driedin vacuo at 40-45° C. to give Compound A (Polymorph II) as an off whitesolid (17.0 g, 85% recovery).

Example 3 (2S, 3S, 4R, 5R)-2-(5tert-Butyl-[1,3,4]oxadiazol-2-yl)-5[6-(4-chloro-2-fluoro-Phenylamino)-9H-purin-9-yl]-tetrahydro-furan-3,4-diol(Compound A) Polymorphic Form I (alternative process)

9-{(3aR,4R,6S,6aR)-6-[5-tert-butyl-1,3,4-oxadiazol-2-yl]-2,2-dimethyltetrahydrofuro[3,4-d][1,3]dioxol-4-ly}-N-(4-chloro-2-fluorophenyl)-9H-purin-6-amine(Intermediate X) may be prepared according to the methods described inWO 99/67262 (Intermediate 63, page 122).

9-{(3aR,4R,6S,6aR)-6-[5-tert-butyl-1,3,4-oxadiazol-2-yl]-2,2-dimethyltetrahydrofuro[3,4-d][1,3]dioxol-4-yl}N-(4-chloro-2-fluorophenyl)-9H-purin-6-amine(Intermediate X, 10 g) was added portion wise to 9:1 v/v TFA/water (38ml) at 20° C. and the mixture stirred for 3-6 hours at 20-25° C. Thereaction mixture is then neutralised by addition over a 1-1.5 h periodto a solution of 880 ammonia (28 ml), water (85 ml) and methanol (127ml) at 35-45° C. The mixture is then cooled to 0-5° C. over a 1 h periodand stirred for a further 0.5 h at 0-5° C.*. The product is collected byfiltration, washed with water (3×50 ml) and dried under vacuum at 50° C.to constant weight to give the product as a white solid (8.42 g, 90.9%yield).* Toluene (10 ml) can be added at this point to give a faster filteringproduct

X-Ray Powder Diffraction

The sample preparation and acquisition conditions were as follows:

Samples were lightly ground and packed into silicon cup with a 12 mm(diameter)×0.5 mm cavity. Data were acquired using a Bruker D8 AdvanceX-Ray diffractometer configured with a Cu anode, primary and secondarySoller slits, secondary monochromator and scintillation counter. Thegenerator was operated at 40 kV 40 mA. Variable divergence andantiscatter slits were set at 12 mm irradiated area, and the detectorslit was set at 0.1 mm. A locked coupled step scan with 0.02 degrees 2-theta step was used. The sample was rotated.

Data obtained for Polymorph I and Polymorph II are shown in Figure I.

Raman Spectroscopy

Raman spectra were acquired using a Nicolet 960 ESP FT-Ramanspectrometer. Samples were held in glass vials; spectra of 5 differentpoints on a sample were averaged. Data collection parameters include:Laser power: 400 mW, Resolution: 4 cm-¹, Sample gain: 1.0, Detector.InGaAs, Beamsplitter: CaF2, Correction: none, Zero filling: none,Apodization: Happ-Genzel, Phase correction: Power spectrum.

Raman spectra of Polymorph I and Polymorph II are shown in FIG. 2.

Photographic image of polymorph I and Polymorph II in spheronised habitare shown in FIG. 3. Images of Polymorphs I and II in the fibrous habitobtained using known procedures are shown by way of comparison.

1-15. (canceled)
 16. A process for preparing(2S,3S,4R,5R)-2-(5-tert-butyl-[1,3,4]-oxadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diol(Compound A) as Polymorph I comprising: a) reacting9-{(3aR,4R,6S,6aR)-6-[5-tert-butyl-1,3,4-oxadiazol-2-yl]-2,2-dimethyltetrahydrofuro[3,4-d][1,3]dioxol-4-yl}-N-(4-chloro-2-fluorophenyl)-9H-purin-6-aminewith trifluoroacetic acid/water; b) neutralizing with aqueous methanolicammonia solution at 25-50° C. over at least one hour; and c) cooling to0-5° C., optionally adding toluene.
 17. A process for preparing(2S,3S,4R,5R)-2-(5-tert-butyl-[1,3,4]-oxadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diol(Compound A) as Polymorph I comprising: a) dissolving Compound A inN,N-dimethylformamide and water wherein the N,N-dimethylformamide:waterratio is in the range 2.5:1 to 1.5:1 and the dilution is at least 15volumes; b) initiating crystallisation by either adjusting thetemperature to less than 25° C.; or adjusting the temperature to lessthan 30° C., and seeding with Polymorph I; and c) optionally, addingtoluene.
 18. A process for preparing(2S,3S,4R,5R)-2-(5-tert-butyl-[1,3,4]-oxadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diol(Compound A) as Polymorph II comprising: a) dissolving Compound A inN,N-dimethylformamide and water wherein the N,N-dimethylformamide:waterratio is in the range 2:1 to 1:2 and the dilution is at least 15volumes; b) initiating crystallisation by adjusting the temperature togreater than 35° C.; and optionally seeding with polymorph II; and c)optionally, adding toluene. 19.(2S,3S,4R,5R)-2-(5-tert-Butyl-[1,3,4]-oxadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diolas Polymorph I in spheronised habit. 20.(2S,3S,4R,5R)-2-(5-tert-Butyl-[1,3,4]-oxadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diolas Polymorph I in a habit obtainable by a process of claim
 16. 21.(2S,3S,4R,5R)-2-(5-tert-Butyl-[1,3,4]-oxadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diolas Polymorph I in a habit obtainable by a process of claim
 17. 22.(2S,3S,4R,5R)-2-(5-tert-Butyl-[1,3,4]-oxadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diolas Polymorph II in spheronised habit. 23.(2S,3S,4R,5R)-2-(5-tert-Butyl-[1,3,4]-oxadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diolas Polymorph II in a habit obtainable by a process of claim
 18. 24. Apharmaceutical composition comprising Polymorph I in a habit accordingto claim 19, and a pharmaceutically acceptable carrier and/or excipient.25. A pharmaceutical composition comprising Polymorph I in a habitaccording to claim 20, and a pharmaceutically acceptable carrier and/orexcipient.
 26. A pharmaceutical composition comprising Polymorph I in ahabit according to claim 21, and a pharmaceutically acceptable carrierand/or excipient.
 27. A pharmaceutical composition comprising PolymorphII in a habit according to claim 22, and a pharmaceutically acceptablecarrier and/or excipient.
 28. A pharmaceutical composition comprisingPolymorph II in a habit according to claim 23, and a pharmaceuticallyacceptable carrier and/or excipient.
 29. A method of treating a patientsuffering from a condition where there is an advantage in decreasingplasma free fatty acid concentration, or reducing heart rate, ortreating a patient suffering from ischemic heart disease, peripheralvascular disease, stroke, pain, CNS disorder, or sleep apnoea comprisingadministering a therapeutically effective amount of Polymorph I of(2S,3S,4R,5R)-2-(5-tert-butyl-[1,3,4]-oxadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diolin a habit according to claim
 19. 30. A method of treating a patientsuffering from a condition where there is an advantage in decreasingplasma free fatty acid concentration, or reducing heart rate, ortreating a patient suffering from ischemic heart disease, peripheralvascular disease, stroke, pain, CNS disorder, or sleep apnoea comprisingadministering a therapeutically effective amount of Polymorph I of(2S,3S,4R,5R)-2-(5-tert-butyl-[1,3,4]-oxadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diolin a habit according to claim
 20. 31. A method of treating a patientsuffering from a condition where there is an advantage in decreasingplasma free fatty acid concentration, or reducing heart rate, ortreating a patient suffering from ischemic heart disease, peripheralvascular disease, stroke, pain, CNS disorder, or sleep apnoea comprisingadministering a therapeutically effective amount of Polymorph II of(2S,3S,4R,5R)-2-(5-tert-butyl-[1,3,4]-oxadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diolin a habit according to claim
 22. 32. A method of treating a patientsuffering from a condition where there is an advantage in decreasingplasma free fatty acid concentration, or reducing heart rate, ortreating a patient suffering from ischemic heart disease, peripheralvascular disease, stroke, pain, CNS disorder, or sleep apnoea comprisingadministering a therapeutically effective amount of Polymorph II of(2S,3S,4R,5R)-2-(5-tert-butyl-[1,3,4]-oxadiazol-2-yl)-5-[6-(4-chloro-2-fluorophenylamino)-9H-purin-9-yl]-tetrahydrofuran-3,4-diolin a habit according to claim 23.